Pain is one of the cardinal signs accompanying
inflammation. The
prostaglandins (PGs), synthetized from
arachidonic acid by
cyclooxygenase (COX)-2, are major bioactive
lipids implicated in
inflammation and
pain. However, COX-2 is also able to metabolize other
lipids, including the
endocannabinoids 2-arachidonoylglycerol (2-AG) and
anandamide (AEA), to give
glycerol ester (PG-G) and ethanolamide (PG-EA) derivatives of the PGs. Consequently, COX-2 can be considered as a hub not only controlling PG synthesis, but also PG-G and PG-EA synthesis. As they were more recently characterized, these
endocannabinoid metabolites are less studied in nociception compared to PGs. Interestingly R-profens, previously considered as inactive enantiomers of nonsteroidal anti-inflammatory drugs (
NSAIDs), are substrate-selective COX inhibitors. Indeed, R-
flurbiprofen can selectively block PG-G and PG-EA production, without affecting PG synthesis from COX-2. Therefore, we compared the effect of R-
flurbiprofen and S-
flurbiprofen in models of inflammatory
pain triggered by local administration of
lipopolysaccharides (LPS) and
carrageenan in mice. Remarkably, the effects of
flurbiprofen enantiomers on
mechanical hyperalgesia seem to depend on (i) the inflammatory stimuli, (ii) the route of administration, and (iii) the timing of administration. We also assessed the effect of administration of the PG-Gs, PG-EAs, and PGs on LPS-induced
mechanical hyperalgesia. Our data support the interest of studying the nonhydrolytic
endocannabinoid metabolism in the context of inflammatory
pain.